Treatment of hydrocarbons



Patented June 29, 1943 James W. Jean, Altadena, Calif.

No Drawing. v Application May 26, 1941,

Serial No. 395,203 1 Claims.

This invention relates to the treatment of liquid hydrocarbons, of greater molecular weight than is suitable for gasoline, derived from petroleum oils or from the distillation of carbonaceous material such as coal, lignite, oil shale or of asphaltic material such as tars, pitches or residues-from petroleum operation, by means of an active catalytic mass, elevated temperatures and atmospheric or elevated pressures to form hydrocarbons of lower molecular weight. and higher anti-knock rating.

.It is generally recognized that in the pyrolysis of hydrocarbon compounds there is an over-all loss in hydrogen, a tendency toward carbon separation and a wider boiling range in the total liquid products than in the original charge. In thermal decomposition and to a large extent in catalytic cracking of crude oils and petroleum distillates the production of hydrogen and fixed hydrocarbon gases is so great that the loss involved in processing the heavy hydrocarbons is exhorbitant and the carbon deposition due to the reduction of the hydrogen-carbon ratio is so great, that, in the case of catalytic'cracking, the activity of the catalyst employed is destroyed in a very short space of time due to the covering of the active faces .01 the catalyst by carbon. In order to avoidthis destruction of catalytic activity it is necessary in present catalytic cracking processes to (1) increase the ratio of feed to catalyst, or (2) decrease the temperature of the reaction. In either case theproduction of light fractions boiling within the gasoline range is sacrificed in order that the catalytic life of the catalyst may be extended and the loss caused by the production of fixed. gases minimized. It is the object of this invention to provide catalysts and a method whereby these objectionable features of present catalytic methods of producing light hydrocarbon fractions from heavier hydrocarbon materials may to a large extent be eliminated.

One specific embodiment of the present in .ntion consists of subjecting liquid hydrocarbons of a molecular weight greater than that desirable in a high grade motor fuel at elevated temperatures in the neighborhood of 650 F.-950 F. and at atmospheric or elevated pressures ranging from 0 to 150 pounds per square inch to the action ofa catalytic mass comprised of granules I of a heavy metal tetraphosphate of the formula Me=P4Ou or of a mixture of these tetraphosphates with pyrophosphates (MezPaOq) and orthophosphates (Me=PO4) for definite periods of contact varying with the nature of the hydrocarbon feed stock. The metal tetraphosphates having the greatest catalytic eiTect are those selected from the elements of group 8 and the. right column of group 1 of the periodic table.

The mixed phosphates referred to above may be made by the action of tetraphosphoric acid (HoP4O1a) upon the oxides of the metals specified above or by the action of the acid upon the pure metals. However the production of the tetraphosphates from the pure metals is a tedious process as the tetraphosphoric acid being a poly acid of the structural formula is easily hydrolyzed to the mono acid and therefore cannot be diluted with water. In its commercial form tetraphosphoric acid is a heavy viscous liquid which is relatively inert at room temperatures and only becomes reactive in metals or metal oxides at slightly elevated temperatures in the neighborhood of .180-300 F. This makes the formation of tetraphosphates from metals subject to difficulty in handling and also causes the production of the meta acid by dehydration of the tetra acid at the temperature necessary to complete the reaction so that the final product contains relatively large amounts of the meta acid which is prone to be converted to atomic phosphorus at the temperatures used in reacting hydrocarbons and to sublime over which is highly undesirable.

Iron oxide, which is the preferred base material for the manufacture of the catalytic mass employed in this invention may be obtained from the ore hematite. As far as has been ascertained the powdered ore containing up to 50% of impurities, largely silicates and traces of metal oxides, is as eflicient as the more expensive purified oxide. The powdered hematite is. mixed with the theoretical amount of commercial tetraphosphoric acid and the resulting paste heated to about 300 F. for a period of time depending upon the rate of reactionand the amount of impurities. At the end of the reaction period the temperature is elevated to about 500 F. to drive of! any water vapor that may result in the reaction product and the hard, dry, porous mass is reduced by fracture to granules of 4 to 16 mesh and is then ready to be placed in the reaction tube.

In this method of manufacture the water released by the action of the acid upon the oxide '(Me,0=+mPlo1=- Me=rnoo+3mo) causes some of the tetraphosphoric acid to be hydrolyzed. although the majority of the water formed is driven oi! as steam at the temperature of reaction, so that side reactions involving pyrophosphoric acid and some orthophosphoric acid are involved with the production of relatively small amounts of pyro and ortho phosphates of the metal used.

As an example of the action or my improved .runs.

7500 ml. of a heavyoil from an asphaltic base with no gasoline fraction derived from the decoking of a high sulphur asphalt was vaporized, heated to 760 F. and passed over my improved catalyst at the rate of 1.5 liquid volumes of hydrocarbon per hour to one volume of catalyst at a pressure of 40 pounds per square inch. This was a one-pass operation with no recycle.

6120 ml. of liquid was recovered as condensate which is equivalent to 81.4% of the total feed. The fixed gases which were highly olefim'c were not measured.

On fractionation of the condensate 2080 ml. of

410 F. end point gasoline was recovered whichwas equivalent to 26.4% of the total feed to the reactor.

Inspection of the gasoline fraction was as follows:

Sulphur 0.36%. ASTM gum L. nigs/IOO m1. Octane number 74.0 I. B. P F 125 5% F 169 F 181 F 200 F 2201 40% F 235 F 251 -F 270 F 290 F 317 F 355 'F 390 EP 410 Resid 1.1 Recovery .1 98.0

12000 mLoi a paraflinic crude was vaporized and passed over my improved catalyst at 700 F. 750 F. and pounds per square inch pressure at the rate of 1.7 liquid volumes of feed per hour to one volume of catalyst. This operation was one pass and one recycle of the heavy ends after the gasoline fraction had been removed. 11,196 ml. of liquid was recovered as condensate representing 93.3% of the total charge to the reactor. On combining the gasoline fractions from the first pass and the recycle, 8,616 ml. of 360 F. end point gasoline was recovered, equivalent to 71.8 of the total feed to the reactor. 7 In neither case of the aforementioned runs was the carbon deposition on the catalyst sufiicient to reduce the catalytic activity of the catalyst.

Copper, another preferred base material for the production of catalytic material useful in this process and a representative of the right hand column of group 1 of the periodic table may be used in the form of cupric oxide. It is treated in a manner identical with that given above for the production of a catalytic mass from iron oxide. In addition the catalytic mass may be extended using the more expensive copper oxide by mixing an extending agent such as a siliceous material composed of diatomaceous earth with the reacting ingredients and the physical properties of the catalytic mass may be improved by the addition of relativelysmall amounts of kaolin clays or preferably bentonite.

phoric acid and calculations of acid necessary must take this fact into consideration. The aluminum tetraphosphates produced by the reaction have the ability to bind the catalytic mass into a more solid whole, but they are not desirable in quantities of more than approximately 15% by weight. Bentonite, consisting largely'of colloidal silica, does not require this calculation and imparts excellent hardness to the catalytic mass.

In practicing the process of my invention the general procedure is to vaporize the hydrocarbons and, after heating the vapors to a suitable tem perature within the range previously stated to pass them downward through stationary masses of granular catalytic material in vertical cylindrical treating columns or banks of catalyst containing tubes in parallel connection. Since the reactions are endothermic it may be necessary to apply some heat externally to maintain the reaction temperatures. After passing through the catalytic zone the products are submitted to fractionation to recover the desired fractions of gasoline, kerosene, distillate, etc., or the heavier fractions not desirable in gasoline may be conden'sed and re-run through the catalytic zone.

If a recycle of the heavier ends is desired they should be first run through a tar separator or a precoker as the downward method of passing the hydrocarbon vapors over the catalytic mass serves to wash the surface of the catalyst and remove some of the deposited carbon and tar which is' carried oii in suspension or solution in the con densing vapors. Also in this as in other catalytic processes there is a tendency for some of the hydrocarbon vapors to polymerize and form tarry substances which if not removed by some formof extraction, deposit upon the catalyst on being re-run due to their high carbon to hydrogen ratio and thus shorten the active life of the catalyst.

Having now fully disclosed my improved method of eiiecting hydrocarbon conversion and the improved catalyst therefor, I claim as my invention:

1. The process for the production of gasoline boiling range hydrocarbons from hydrocarbons of greater molecular weight by contacting vapors of hydrocarbons at temperatures ranging approximately from 650 to 950 F. with a granular catalytic mass composed of tetraphosphates of the metals of the .eighth group of the periodic table containing traces of ortho and ro phosphates of the same metal.

The aluminum oxide of the clay is highly reactive with the tetraphos- 2. The process for the production of gasoline boiling range hydrocarbons from hydrocarbons of. greater molecular weight by contacting vapors of hydrocarbons at temperatures and pressures ranging approximately from 650 to 950 F. and 0 to pounds per square inch with 'a granular catalytic mass composed of tetraphosphates of the metals of the eighth group of the periodic table containing traces of ortho and pyro phosphates of the same metal.

3. A catalyst for the formation of light hydrocarbons from heavier hydrocarbons composed of tetraphosphates of the metals of group 8 of the periodic table.

4. A catalyst for the formation of light hydrocarbons from heavier hydrocarbons composed of tetraphosphates of the metals of group 8 of the periodic table and a binder.

5. A catalyst for the formation of light hydrocarbons from heavier hydrocarbons composed of tetraphosphates of the metals of group 8 of the periodic table and bentonite as a binder.

JAMES W. JEAN. 

